With the continued development of wireless technology and wireless applications, the demand for faster mobile data rate keeps increasing rapidly, particularly for indoor users. To provide indoor data services, a Customer Premise Equipment (CPE) such as a router or a modem is commonly deployed for an indoor customer.
A conventional wire-backhauled CPE is deployed indoor to provide wireless or wired data services to a Local Area Network (LAN) of an indoor customer, and connects to the data network of an Internet Service Provider (ISP) through an optical fiber or cable connection. Unfortunately, the need of an optical fiber or cable connection to every wired CPE significantly increases the network deployment cost of an ISP.
An alternative device is a wireless-backhauled CPE. Instead of an optical fiber or cable connection for a wire-backhauled CPE, a wireless CPE has a wireless connection to a base station (BS) of an ISP where the BS provides a wireless backhaul connection to the wireless CPE. In sub 6-GHz frequency bands, the wireless-backhauled CPE can be deployed indoor, or the link antenna or antennas of the wireless-backhauled CPE can be deployed outdoor in order to achieve a stronger backhaul link with the BS. Unfortunately, the sub 6-GHz frequency bands widely used in wireless systems today is quite crowded, so conventional means using these frequency bands may not be sufficient to meet the growing data demand, as shown in “Millimeter Wave Mobile Communications for 5G Cellular: It Will Work!” by T. S. Rappaport et al. published in IEEE Access, vol. 1, pp. 335-349, 2013 (Rappaport et al 2013).
Exploiting the much broader available spectrum of centimeter and millimeter wave above 6-GHz, e.g., 28 GHz, 60 GHz, or even higher bands, has been considered as a promising solution to overcome the global spectrum shortage challenge of the upcoming Fifth Generation (5G) wireless systems (Rappaport et al 2013). For the sake of simplicity, all frequency bands of centimeter and millimeter or even shorter wavelength are all referred to millimeter wave (mmWave) hereafter.
The large bandwidth of a mmWave system could provide high data rate services, which is well suited for a wireless-backhauled CPE. However, the coverage of a mmWave BS is limited by its strong propagation directivity, large propagation loss, and high sensitivity to blockage, as shown in “Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges,” by S. Rangan et al. published in Proceedings of the IEEE, vol. 102, no. 3, pp. 366-385, March 2014. As a result, even deploying the link antenna array or antenna arrays that offer high array gain outdoor facing the BS, the working location of a mmWave CPE (mmCPE) is still limited to the Line-of-Sight (LoS) coverage area of the BS. FIG. 1 illustrates a simple example where one mmWave BS 1 serves one mmCPE 2 for one Customer Premise (CP) 3 in its LoS coverage while cannot serve another mmCPE for another CP out of its LoS coverage blocked by one obstacle 4. In this example, both CP1 and CP2 need data service using mmCPE1 and mmCPE2, but only CP1 is in the LoS coverage area of the BS, while CP2 that is blocked by the obstacle hence out of its LoS coverage area. As a result, the BS can only serve CP1 through mmCPE1, but cannot serve CP2 due to the large blockage loss in mmWave systems. In order to offer services to CP2, either another BS is deployed to provide LoS coverage to CP2, or an optical fiber or cable backhaul link needs to be deployed for CP2. Unfortunately, both methods increase the network deployment cost.
This invention provides a method and apparatus for a mmWave BS to effectively serve mmCPEs out of its LoS coverage area by employing Enhanced mmCPEs (EmmCPEs).